Knocking in 1973 RT360
Fuel wise, I've been using 93 ethanol pump gas. Couldn't find much information on if ethanol gas causes knocking in old engines, just that it can sometimes cause them to run poorly and clog jets. Could the gas be a culprit? And are there any additives that could remedy the problem or should I just find ethanol free gas?
Finally, I read elsewhere on the forum that you can differentiate crankshaft knock from piston knock by pitch, crankshaft knock being lower and piston knock being higher, any merit to this?
RT3Sam wrote: So I see no one has responded. Its hard to advise on engine knocking without actually hearing your engine. But if it were me, I would order a gasket kit and a clymer manual off e-bay and start disassembly of your engine. Its better to do a full inspection of the top end and crank and not take a chance at exploding the engine and causing more damage. just my $0.02.
Clymer, CLYMER........ How very dare you!
What's wrong with the Yamaha Service Manual in the Tech Library (see link below)?
piston slap sounds like a rattle at idle and when the engine is decelerating, it goes away under load.
here is my bike with piston slap:
Rod bearings going out usualy makes a really loud knock.
crankshaft main bearings will make bad vibration and sound like a low grinding/grumbling/howling.
akara1 wrote: Rod bearings going out usually makes a really loud knock.
If the rod bearing is knocking that is impending doom leading to a trashed crank & top end in a hurry!
But...most likely you're hearing piston slop. Take a video, post it on youtube, link it to this thread and people will chime in.
I've also had the front screw on the chrome exhaust guard come loose and fall out leaving the guard to rattle. I used Locktite after that. Good luck hope this helps.